Herbicidal method employing cyano-



United States Patent Ofice 3,125,432 HERBICIDAL METHOD EMPLOYING CYANO-PHENYL METHYL UREAS Charles W. Todd, Thombury Township, Delaware County,Pa., assignor to E. I. du Pont de Nemours 'and Company, Wilmington,Del., a corporation of Delaware No Drawing. Filed July 18, 1960, Ser.No. 43,330

' 1 Claim. (Cl. 71-2.6)

This invention relates to a class of cyanophenyl methyl ureas and tocompositions containing these compounds.

The cyanophenyl methyl ureas of the invention are represented by theformula where X is hydrogen or chlorine; n is 1 or 2; Z is oxygen orsulfur; R is hydrogen or methyl; and R' is hydrogen or alkyl of lessthan 5 carbon atoms.-

The ureas of this invention can be prepared by conventional methods, forexample,,by reaction of aliphatic and aromatic primary and secondaryamines with an isocyanate isothiocyanate, carbamyl chloride, orthiocarbamyl chloride. The following equation illustrates one methodwith respect to the preparation of the .cyanophenyl methyl ureas of thisinvention:

ONQ NHGH, oloomomn OH: H;

The above reaction is accomplished by bringing the amine in contact withone or the other of the reactants specified, usually in chemicallyequivalent amounts and, if necessary, heating. It is in many casespreferable to use an excess of the amine, for example, to 20% molarexcess.

Although not in general essential, inert liquid media, for example, drybenzene, dry toluene, dry anisole, and the like can for the most part beadvantageously employed. It is desirable to use an acid acceptor, forexample, a tertiary amine suchas triethylamine, dimethylaniline,pyridine, and the like. Ordinarily, temperatures in the range of 0 to100 C. or preferably to 75 C. aresatisfactorily employed for the abovereactions.

Other methods which can be used in the preparation of thecyanophenylureas of this invention are illustrated by the followingequations:

A 3,125,432 Patented Mar. 117, 1964 ent on the phenyl group isortho-para directing. For example, monuron, that is3-(p-chlorophenyl)-1,1-dimethylurea, contains a chlorophenyl group; and,as is well known, halogens are ortho-para directing with respect to abenzene nucleus. V

To use these substituted ureas as herbicides, ordinarily they areformulated into herbicidal compositions by admixing one or more of thesubstituted ureas, in herbicidally effective amounts, with aconditioning agent of the kind used and referred to in the art as a pestcontrol adjuvant or modifier in order to provide formulations adaptedfor ready and efiicient application to soil or weeds (i.e., unwantedplants) using conventional applicator equipment.

Thus herbicidal compositions, or formulations, are prepared in the formof either powdered solids or liquids. The liquid compositions, whethersolutions or dispersions of the active substituted urea in a liquiddiluent, ordinarily contain as a conditioning agent a surface-activeagent in amounts sufficient to render the liquid composition readilydispersible in water for application as an aqueous spray. The powderedsolid herbicidal compositions preferably also contain a surface-activeagent in an amount sufiicient to impart water dispersibility to thepowdered compositions, although the surface-active agent can be omittedif it is desired to apply the compositions by dusting rather thanspraying. However, even though the surface-active agent be omitted theherbicidal composition will still contain, of course, a powdered solidcarrier or diluent as a conditioning agent.

The surface-active agents employed can be of the anionic, cationic ornonionic type. They include, for example, sodium oleate, sulfonatedpetroleum oils, alkyl aryl sulfonates, sodium lauryl sulfate,polyethylene oxides, lignin sulfonates, and other surface-active agents.A detailed list of such agents is set forth in an article by McCutcheonin Soap and Chemical Specialties, volume 31, Nos. 7-10 (1955).

Generally, the surface-active agent will not comprise more than about 5to 15% by weight of the composition, and in certain compositions thepercentage will be 1% or less. Usually the minimum lower concentrationwill be 0.1%.

Powdered or dust compositions of the invention whether or not alsomodified with a surface-active agent to make them water dispersible areprepared by admixing one or more of the active substituted ureas withfinely divided solids, preferably, tales, natural clays, pyrophyllite,diatomaceous earth, and flours such as walnut shell, wheat, redwood,soya bean, and cotton-seed flours. Other inert solid carriers which canbe used to prepare the herbicidal formulations include magnesium andcalcium carbonates, calcium phosphate, sulfur, lime, etc., either inpowder or granular form. The percentage by weight of the essentialactive ingredients will vary according to the mannor in which thecomposition is to be applied but, in general, will be 0.5 to by weightof the herbicidal composition.

The active substituted ureas canbe dissolved in organic solvents such ascyclohexanone, methyl ethyl ketone, cyclohexanol, furfural, acetone,isobutanol, ethanol, isopropylacetate, and the like, in the preparationof liquid compositions of the invention. Concentrated water-dispersibleliquid compositions can preparedby incorporating the ureas andsurface-active agents in various organic liquids such as furfural,methanol, rsopropanol, isobutanol, xylol, cresol, cyclohexanone,acetone, methyl ethyl ketone, kerosene, trichloroethylene,dimethylformamide, dimethylacetamide, alkylated naphthalcnes, and thelike. Such compositions are readily dispersible in water and provideexcellent aqueous herbicidal sprays for field application. Theproportion of surface-active dispersing agent to urea can be 0.1 to 100%by weight in the water-dispersible herbicidal compositions.

The herbicidal compositions of the invention can also have incorporatedtherein oils, fats or similar vehicles such as cottonseed oil, oliveoil, lard, parafiln oil, hydro ted ve table oils, etc.

ihe herbicidal compositions are applied either as a spray or a dust tothe locus or area to be protected from undesirable plant growth,commonly called weeds, i.e., plants growing where they are not wanted.Such application can be made directly upon the locus or area and theweeds thereon during the period of weed infestation in order to destroythe weeds, or alternatively, the application can be made in advance ofan anticipated weed infestation to prevent such infestation. Thus, thecompositions can be applied as aqueous fohar sprays but can also beapplied as sprays directly to the surfaceof the soil. Alternatively, thedry powdered compositions can be dusted directly on the plants or on thesoil. For some purposes, as in the treatment of ponds and lake bottomsand brush, it will be convenient to use a pellet form of thecomposition.

In another method of application for weed control,

ureas are incorporated with fertilizers to form either powdery orgranular herbicidal compositions that can be used in the cultivation ofagricultural crops.

The-active ingredients are, of course, applied in amount suilicient toexert the desired herbicidal action. The amount of herbicidally activecompounds present in the compositions as actually applied for destroyingor preventing weeds will vary with the herbicidal activity of the activeingredients, the purpose for which the application is being made (i.e.,whether for short term or long term control), the manner of application,the particular weeds for which control is sought, and like variables.Certain of the specific examples to follow will illustrate various kindsand amounts of application and the results obtained thereby. In general,the herbicidal compositions as applied in the form of a spray or a dustwill contain from about 0.02% to 95% by weight of herbicidally activeingredient.

The solid and liquid compositions described and employed herein forapplication of the essential active herbicidal ingredient all have thecommon property of permitting application of the herbicidal compositionsthrough suitable jets, nozzles, or spreaders adapted for the handling ofgranular materials onto the plants being treated and will, forconvenience, be designated as fluent carriers." The fluent carriers withwhich this invention is primarily concerned are non-solvent fluentcarriers.

These compounds have utility as herbicides, both for weed control incropland at relative low rates of 1 to 4 pounds .per acre and forcontrolof undesirable annual millet, barnyard grass, Johnson grass, cheat,lamb'squarters, pigweed, chickweed, and wild mustard growing in corn,sorghum, sugar cane and certain woody ornw 'rnentals. Some of theundesirable weeds on non-cropland that are controlled includequackgrass, Johnson grass, pigweed, lambs-quarters, crabgrass, charlock,volunteer clovers, ragweed, mares-tail and buttonweed.

In order that the invention may be better understood, the followingexamples are given in addition to the examples already given above. Thenumbers following the tabulated ingredients represent parts by weight ofthe ingredients in the respective compositions.

EXAMPLE 1 A solution of 118 parts by weight of p-arninobenzonitrilecontained in 400 parts by weight of anisole is added dropwise to astirring solution of parts by weight of phosgene contained in 500 partsby weight of EXAMPLE 2 A solution of 17.7 parts by weight ofm-aminobenzonitrile dissolved in 30 parts of xylene is added dropwisewith stirring to,a solution of 17 parts by weight of phosgene in 170parts of xylene. The mixture is heated to reflux temperature for twohours. Dry nitrogen is passed through the hot solution to remove thelast traces of HCl gas. The solution is then cooled and dimethylaminegas is added until the mixture is "saturated and basic to litmus. Theprecipitate is filtered and washed twice with n-pentane to obtain 25parts by weight of crude product. This product is recrystallized fromethyl acetate to-obtain 16 parts of 3-(m-cyanophenyl) 1,1-dimethylurea,which has a melting point of 159-160.5 C.

AnaIysir.Calcd. for c,,,H,,N,o= N, 22.22. Found: N, 21.48; 21.41.

EXAMPLE 3 A solution of 21.5 grams of 3-cyano-4-chloroaniline, preparedas described in J. Indian Chem. Soc. 10, 309 (1934), in a mixture of 500milliliters of xylene and 75 milliliters of dioxane, is added rapidly,below the surface, to a solution of 21.0 grams of phosgene in 210milliliters of xylene, while stirring. A heavy precipitate forms. Themixture is heated to reflux, with the solid dissolving at around C., andnitrogen is introduced for five minutes to remove most of the hydrogenchloride found in the solution. The solution is then cooled,- and anexcess of dimethylamine gas is introduced. A white precrpitate forms.After stirring for 30 minutes, the mixtu re is cooled in ice andfiltered, and the solid is washed with water. The white crystallineproduct is 3-(3-cyano- 4-chlorophenyl)-1,1-dimethylurea, having a netweight of 35 grams and a melting point of 1527.C. Recrystallrzation froma water-ethanol mixture raises the melting point to 157-8 C.

Analysis.-Calcd. for C H ClN Oz C, 53.70; H, 4.51; Cl, 15.95; C, 53.60;H, 4.58. Found: Cl, 15.84.

EXAMPLES 4-11 By substituting molecular equivalent amounts of phosgene,thiophosgene, substituted aniline or alkyl amines shown in Table I forthe phosgene, p-aminobcnzonitrile and dimethylamine of Example 1, thefollowing compounds of this invention are prepared:

parts by weight of. N-methyl-2-chloro-4-cyanoaniline. The reactiontemperature is allowed to rise to 70-80 C.

Table I Exilvmple Anil U a Alk 1x i U a 11 Pod o. ine se mne se r notObtained y 01001 Used o-amino-benzonlmethylamine thiophosgeneu3-(2-eyanopheny1)-1-methyl-2-thiourea.

e. 2-cyano-4-ehloromethyl ethyl phosgene3-(2-cyano-4-chloro-phenyl)-1-ethyl-1- aniline. amine. methyl-urea.m-aimirllo-benzoisopropylamine... thiophosgene3-(3-cyanophenyl)-1-isopropyl-2-thion r a. urea.2-chloro-3-eyanomethylisopropyl do3-(2-ehioro-3-cyanophenyi)-1-metl1yl-1- aniline. amine.isopropyl-Z-thiourea. 3,4-dichloro-5 isobutylamine do 6-(3,4dichloro-5-eyano-phenyl)-l-isocyano-anillne. buty1-2-thiourea.2-eyauo-3,4-d1- dimethyl amine--. phosgene5(2eyano-3,4-dichlorophenyl)-l,1-diehloroaniline. methylurea.3-eh1oro-4-cyanomethyl n-butyl thiophosgene5-(3-chloro-4-cyauo-phenyl)-1-methy1-1 aniline. amine.n-butyl-2-thiourea. 11 do dimethyl amine.-. phosgene3-(3'chloro-4-cyano-phenyl);1,l-dimethylurea.

EXAMPLE 12 EXAMPLES 13-16 By substituting molecular equivalent amountsof methyl cyanate or methyl isothiocyanate and the substituted aniandmaintained at this temperature for an additional two hours after theaddition has been completed. After cooling the reaction, sufficientwater is added to precipitate essentially pure3-(2-chloro-4-cyanophenyl)-1,1-3-trimethylurea out of solution.

EXAMPLES 18-25 By substituting molecular equivalent amounts of N,N-dialkyl carbamyl chlorides and substituted anilines listed in Table IIIfor dimethyl carbamyl chloride and N-methyl- 2-chloro-4-cyanoaniline inExample ,17, the compounds of this invention of Table III are similarlyprepared.

Table III Example Substituted Aniline Used Carbamyl Chloride ProductObtained N 0. Used N-methyl-2Ardichloro-5- methyl n-propyl3-(2,4-dichloro'5-eyanophenyl)- eyanoaniline. carbamyl chloride.1,3-dimethyl-l-propylnrea. N-m ethyl-mcyanoanlline dinlileithyl earbamyl3-(3-eyanophenyl)-3,1,1-trimethylurea.

c on e. N -methyl-3,4-diehloro-5- dimethyl carbamyl3-(3,4-diehlore5-cyanophenyl)-3,1,

cyanoaniline. chloride. l-trimethylurea. N-methyi-pcyananiline N methylpropyl 3-(4-eyanophenyl)-1,3-dimethyl thiocarbamyl l-propyl-Z-thiourea.chloride. N -methy1-2-ehloro-4- dimethyl thiocar-3-(2,chloro-4-cyanophenyl)-3,l,1-

cyanoaniline. bamyl chloride. trimethyl-2thiourea. N-rnethyl-m-cyanoaniline dimethyl carbamyl 3-(3-cyanophenyl)-3,1,l-

chloride. trimethylurea. N -methyl-2-cyano-5- dimethyl carbamyl-(2-cyano-5chlorophenyl)-3,l,1-

chloroaniline. chloride. trimethylurea. N-methyl-2-chloro3- methyln-butyl 1&(2-ehloro-3-cyanophenyl) 1,3-

eyanoaniline. tlgliocabamyl dimethyi-1-n-butyl-2-thiourea.

c on e.

lines as described in the following Table II for methyl isocyanate and-N-methyl-p-cyanoaniline of Example 12, the compounds shown in Table IIare similarly prepared.

Table II Example Substituted Isocyanate Product Formed N o. Aniline UsedUsed 13 3-eyauo-4-ch1oro-N- methyl 5-(3-eyano-4-chloromethylaniline.isocyaphenyl)-l,3-dimethnate. ylurea. l4 3-chloro-4-cyano-N- do5-(3-cliloro-4-cyanomethylauiline. p{1enyl)-l,3-dimethyurea. 153-cyano-N-methylauimethyliso- 3-(3-eyanophenyD-L3- line.thitocyadimethyl-Z-thiourea.

na e. 16 2-cyano3A-dichloro- ..-do 5-(2-cyano-3,4-dichloro-N-methylaniline. phenyl)-1,3-

methyl-2thiourea.

EXAMPLE 17 A mixture of 79 parts by weight of pyridine and 107 pansgbyweight of dimethyl carbamyl chloride is heated for 0.5 hour at 60 C.This mixture is cooled to C. and gradually (while stirring) diluted with182.5

EXAMPLE 26 Water-dispersible p0wders.-The following powderedcompositions are adapted for dispersing in water for application as aspray for the destruction and prevention of weeds. They are made byintimately mixing the listed ingredients using conventional mixing orblending equipment and then grinding the mixture to give "powders3-(o-cyanophenyl)-l-methyl-2-thiourea 80 Attapulgite clay 16.75

The above formulations are extended with 250 gallons of water andapplied at the rate of 35 pounds of the active ingredient per acre witha t uck-mounted pressure sprayer to a heavy infestation of annual andperennial broadleaf and grass species. Excellent kill of vegetation isevident. F

The formulation described in B above is applied at the rate of 4 pounds(active ingredient) in 40 gallons of water for the directedpost-emergence control of manual weeds growing in omamentals (privet).Excellent con trol of crabgrass, foxtail, pigweed and mustard isobtained without adverse effects on the privet.

EXAMPLE 27 Oil-water dispersible powder.-The following powderedcompositions are adapted for use in the preparation of a spraycomposition usi. g either an oil, water, or a combination of oil andwater as the liquid diluent. The powders are made by mixing and grindingas in the case of the powder of Example 1.

3-(4-chloro-3-cyanophenyl)-1-methylurea 60 Polyethylene oxide ester ofmixed fatty and resin acids Disodium phosphate 2 Attapulgite clay 28 B3-(Z-cyano-S-chlorophenyl)-1,l-dimethylurea 65 Blended polyalcoholcarboxylic esters and oil-soluble sulfonates Disodium phosphate 2Fuller's earth 28 3-(p-cyanophenyl)-1-methylurea 65 Polyethylene oxideesters of mixed fatty and resin acids 5 Fuller's earth 30 D 3 (2 chloro4 cyanophenyl)-1-n-butyl l-methylurea 60 Blended polyalcohol carboxylicesters and oil-soluble sulfonates Fine silica 5 Attapuigite clay Theabove-listed compositions are diluted with 200 gallons of diesel oil andapplied at the rate of 20 pounds of the active ingredient per acre froma railroad spray car. Excellent control of both annual and perennialweed species (including quackgrass, Bermuda grass, ragweed, pigweed,crabgrass and chicltweed) is obtained.

EXAMPLE 2a Water-disper'sibIe liquid compositt'om-The followingcompositions are in a liquid form adapted for addition to C-3-(3,4-dichloro-5-cyanophenyl)-1,l-dimethylurea' 50 Oleyl ester ofsodium isothionate 1 Sodium lignosulfonate l Disodium phosphate 2 Chinaclay (kaolin) 46 water to give aqueous, dispersions for application assprays. The urea herbicides are generally quite insoluble in most oils.Therefore, the liquid compositions ordinarily are not complete solutionsbut rather are dispersions of solid in an oil. The liquid or fluidcompositions shown are prepared by thoroughly mixing and dispersing theactive compounds and conditioning agents in the organic liquid diluents.l

3-(4-cyanophenyl)-1,l,B-trimethylurea 30 Xylene 63 Blend of polyalcoholcarboxylic esters and oil-soluble sulfonates 3(2,3-dichloro-4-cyanophenyl.)-1,l-dimethyl-Z-thiourea 40 Straight-chainhydrocarbon Polyethylene oxide esters of mixed fatty and resin acids 5 3(3,4 dichloro-S-cyanophenyl)-1,3-dimethyl-1-isopropyl-Z-thiourea 30Sulfonated petroleum oil (oil-soluble) l0 Kerosene (aliphatichydrocarbons) These compositions are extended with 250 gallons of waterand applied at the rate of 20 pounds of the active ingredient per acrein lumber yards with a speciallyadapted hand pressure sprayer. Excellentcontrol of quack grass, crabgrass, cheat, pigweed and lamb's-quarters,is obtained.

3-(3-cyano-4-chlorophenyl)-1,l-dimethylurea 40 Straight chainhydrocarbon 55 Polyethylene oxide esters of mixed fatty and resin acids5 This composition is extended uiith 35 gallons of water and applied atthe rate of 3 pounds (active ingredient) per acre as a directedpost-emergency spray to emerged young weeds growing in corn. Excellentcontrol of crabgrass, foxtail and pigweed is obtained without visibleinjury to the corn. 7

EXAMPLE 29 Granular composltian.The following compositions are adaptedfor application by means of fertilizer spreader apparatus or similarequipment. The compositions are readily prepared by mixing theingredients with water to form a paste. The paste is then extruded,dried, and ground to give the desired granular size. Preferably, thegranules will be in the order of one-thirty second to onequarter inchdiameter.

3 (2-,4-dichloro-S-cyanophenyl)-l,3-dimet.hyl-l-sec.

butylurea Methyl cellulose l Disodium phosphate 1 Sodium sulfate(anhydrous) 10 Pelleting clay 83 B-(m-cyanophenyl)-l,l-dimethylurea 8Portland cement 40 Low viscosity polyvinyl alcohol l Attaclay 51 Thesegranular compositions are applied at the rate of 35 pounds of the activeingredient per acre by means of a fertilizer spreader to control weedson forest fire lanes or by hand for control of undesirable vegetationaround highway signs and fence posts. Outstanding control of a mixedpopulation of annual and perennial broadleaf and grass species isobtained.

This application is a continuation-in-part of my copending applicationSerial No. 666,757, filed June 19, 1957 (now abandoned), which in turnis a continuationin-part of application Serial No. 412,045, filedFebruary 23, 1954 (now abandoned), which in turn is acontinuation-in-part of application Serial No. 186,118, filed September21, 1950 (now abandoned).

I claim:

The method comprising applying to an area to be protected from undesiredvegetation, in an amount sufiicient to exert herbicidal action, acyanophenyl methyl substituted urea of formula X. R Z R uito...

where X is chlorine, n is 0-2 inclusive; Z is selected from the groupconsisting of oxygen and sulfur; R is selected from the group consistingof hydrogen and methyl; and R is selected from the group consisting ofhydrogen and alkyl of 1-4 carbon atoms inclusive.

References Cited in the file of this patent UNITED STATES PATENTS2,538,008 Keyes et al. Ian. 16, 1951 1,655,444 Todd Oct. 13, 19532,655,534 Searle Oct. 13, 1953 2,780,535 Snyder Feb. 5, 1957 2,787,574Oneill et al. Apr. 2, 1957 2,876,088 Hill et al. Mar. 3, 1959 2,897,229Stuehmer et a1 July 28, 1959 3,031,292 Todd Apr. 24, 1962 OTHERREFERENCES Dyson et al.: J. Chem. Soc., 1927, pp. 442-443. Jacini: Gazz.Chim. Ital., 77 (1947), p. 310. Doub et al.: Journal of AmericanChemical Society,

1958, vol. 80, pp. 2205-2216.

